This invention relates to a long-hair cutter of the type identified in the prior-art portion of claim 1.
A long-hair cutter unit of the type initially referred to is known from DE 38 19 055 C2. To achieve face-level engagement between the sharp cutting edges of the cutting comb and cutting blade a hardened cutting blade is face-ground on one or both sides, taking care to maintain a uniform thickness of the cutting blade. Grinding off the rolling skin of the cutting blade causes the material to distort by bending upon removal of the cutting blade from the grinding device. This arbitrary bending of the cutting blade rules out its optimal cooperation with the bearing surface of a dimensionally stable cutting comb. In order to adapt the form of the bent cutting blade so that it conforms with the plane bearing surface of the cutting comb provision is made according to this printed specification for a pressure lip that is made of both an elastically and plastically deformable material and acts on the cutting blade.
From EP 0 652 085 A1 it is known to grind the bearing surfaces of the cutting teeth of one of the two cuttersxe2x80x94the cutting comb or the cutting bladexe2x80x94of a long-hair cutter to a slightly concave shape only in parallel direction to the teeth, while the other of the two cutters is ground slightly concave only in parallel direction to the row of cutting teeth in the area of the bearing surfaces of the cutting teeth between the two outermost cutting teeth. This slightly hollow grinding is produced by a rotatably drivable grinding wheel with a curved or arched peripheral surface whose radius of curvature has a value of twelve meters. When the crosswise hollow ground cutters are assembled the result is a four-point support that rules out perfect contact between the cutting teeth when the long-hair cutter is put into operation. Furthermore, the hollow grinding of the two cutters causes more or less of the rolling skin to be abraded from the two cutters, resulting accordingly in an undesirable additional curvature that hinders an optimal cooperation of the crosswise hollow ground cutting teeth.
It is an object of the present invention to provide a long-hair cutter of the type initially referred to, in which optimal contact between the cutting comb and the cutting blade is guaranteed in the assembled state.
According to the invention this object is accomplished with a long-hair cutter of the type initially referred to by the features specified in claim 1.
A further solution for accomplishing this object is characterized by the features specified in claim 2.
An essential advantage of the solutions of the invention is that it is possible to individually adapt the engagement surface of the cutting blade, which is movable in a reciprocating fashion, in relation to the bearing surface of a cutting comb. Two different production methods are available for producing the curvature of a cutting blade whereby, without any stock being removed from the cutting blade, the cutting blade is forced to adopt the necessary curvature or curvatures, guaranteeing that the cutting surface of the cutting blade adapts to and makes sliding contact with the bearing surface of the cutting comb, while at the same time a necessary restoring force or elasticity of the bent cutting blade is ensured.
A preferred embodiment of the invention is characterized in that the curvature of the engagement surface of the cutting blade is defined by a sequence of arch elements of similar and dissimilar curvature, with the junctions connecting the arch elements being provided as cutting blade bending points for adapting the engagement surface of the cutting blade to conform with the bearing surface of the cutting comb under the action of the pressure of the spring element. With this embodiment an effective adaptation of the engagement surface on the cutting blade to the form of the bearing surface of the cutting comb is already guaranteed when the longitudinal dimension of the cutting blade is divided into at least three arch elements. With this embodiment there should preferably be at least two curvatures with coincidental radii and one curvature with a deviating radius. Adapting the engagement surface of the cutting blade to conform with the bearing surface of the cutting comb is promoted in that the curvature with the deviating radius is provided between two curvatures with identical radii.
According to a further advantageous embodiment of the invention provision is made for the curvature of the engagement surface of the cutting blade to be defined by a sequence of arch elements of identical curvature, with the junctions connecting the arch elements being provided as cutting blade bending points for adapting the engagement surface of the cutting blade to conform with the bearing surface of the cutting comb under the action of the pressure of the spring element. This embodiment is suitable particularly for cutting blades whose engagement surface cooperates with a plane or slightly concave or slightly convex bearing surface of a cutting comb. In addition, this embodiment is particularly well suited for ensuring contact with the bearing surfaces of cutting combs that have production-induced deviations in the surface structure of the bearing surface.
According to an embodiment of the invention provision is made for the longitudinal dimension of the cutting blade to be divided into arch elements by at least two bending points.
According to a preferred embodiment of the invention provision is made for at least two rows of bending points to be arranged parallel to a longitudinal dimension of the cutting blade.
According to a further embodiment of the invention provision is made for the wide dimension of the cutting blade to be divided into arch elements by at least one bending point. This approach promotes the pressing of the engagement surface of the cutting blade against the bearing surface of the cutting comb under the action of pressure from at least one spring element.
In a further embodiment of the invention provision is made for the bending point to be formed by a continuous gradual adaptation of the arcuate curvature of an arch element to conform with the arcuate curvature of the adjoining arch element. This adaptation prevents a kink forming in the curved path of the cutting blade.
A preferred embodiment of the invention is characterized in that provision is made for at least two spring elements such that the relative distance of one spring element to one end of the cutting blade is equal to the relative distance of the other spring element to the other end. In a further aspect of this embodiment provision is made for the relative distance of the spring elements to be essentially equal to the relative distance of one spring element to one end of the cutting blade. This approach promotes the conforming of the curvature of the cutting blade with the cutting comb while maintaining its restoring force or elasticity, and it effects a balanced engagement and sliding action of the cutting blade relative to the cutting comb.
An advantageous embodiment of the invention is characterized in that the direction of the pressure exertable by a spring element is directed essentially onto one bending point. This promotes the changing of form of the respective curvatures of the cutting blade adjoining the bending point. An optimal engagement and cutting action of cutting comb and cutting blade is guaranteed in that the hardened cutting blade with bending points has an elasticity or restoring force that counteracts a permanent deformation of the curvature of the cutting blade under the action of pressure from the spring element.
According to a further embodiment of the invention provision is made for the arcuate form and the bending points of the arch elements of the cutting blade to be manufacturable by embossing using an embossing die and an embossing pad. A further manufacturing method for the cutting blade is characterized in that the arcuate form and the bending points of the arch elements of the cutting blade are manufacturable by varying the compressive stress of the rolling skin of the hardened blade. The advantage of this method is that the engagement surface of the cutting blade is variable partially and individually such that both similar and dissimilar compressive stresses are partially produced in the rolling skin of the hardened cutting blade, which stresses result in similar and dissimilar curvatures of the cutting blade. Using this method enables optimal control with respect to the conformance of the engagement surface of the cutting blade to the bearing surface of the cutting comb. Preferably, the compressive stress of the rolling skin is produced by means of a laser beam of both constant pulse energy and variable pulse energy in order to achieve the compressive stress and hence the curvature required at the respective place on the engagement surface of the cutting blade.